Molecular epidemiological tracing of HIV-1 outbreaks in Hainan island of southern China

Abstract

Objectives: To determine the prevalence of HIV in Hainan island and the molecular epidemiological linkages related to risk factors of viral transmission. Methods: A governmental HIV/AIDS surveillance program, HIV serological study was conducted in volunteers from several high-risk groups between 1991 and 2006 in Hainan province. By phylogenetic reconstruction, we performed a molecular epidemiological tracing in a representative subset of the HIV-1-seropositive individuals diagnosed during this survey. Results: Of 499 752 volunteers, 523 (0.1%) accumulated cases of HIV-1 infection (69.2% needle-sharing drug users, 19.3% heterosexually acquired adults, 3.3% receivers of blood transfusion, 0.8% children born from HIV-1-infected mothers, and 7.7% remained unknown) were diagnosed. Among 83 patient samples examined (70 were infected with HIV-1 subtypes CRF01_AE and eight, two, one, one, and one were B', C, CRF08_BC, B, and a new CRF01_AE/B' recombinant, respectively), 66 (79.5%) were segregated into one large cluster (59 sequences) (founder effect) and one small cluster (three sequences) of CRF01_AE, one small cluster (two sequences) of B', and one small cluster (two sequences) of C. Phylogenetic and epidemiological linkages confirmed four heterosexual transmission events and rejected two potential heterosexual transmission suggested by contact tracing. Only two cases of CRF01_AE showed mutations conferring resistance to nucleoside and nonnucleoside reverse transcriptase inhibitors. Conclusion: The reconstruction of current HIV-1 outbreaks by molecular epidemiological tracing is helpful for identifying epidemic sources and for defining prevention strategies.